Plant-parasitic nematodes can cause severe yield loss of agronomic crops in Florida. Chemical products for managing plant-parasitic nematodes are called conventional nematicides. There are a few nematicides registered for use in Florida; however, some can only be used on one or two agronomic crops. Nematicides must be applied as indicated on the product label, including the crops listed and methods described. As an aid for Florida agricultural professionals, conventional, chemical-based nematicide products labeled and available for Florida agronomic crops at the time of publication are listed in Table 1.
Conventional nematicides can be divided into two categories: fumigants and nonfumigants. Fumigants are broad-spectrum pesticides where the active ingredient moves through the soil as a gas. Fumigants are not taken up by plants or bound by soil, so they do not have a long period of residual pesticidal activity. Nonfumigants are formulated in liquid or granular states and are moved through the soil by water. Nonfumigants may have activity against multiple pests, particularly if they contain more than one active ingredient, but generally, they have a narrower spectrum of activity than that of fumigants. Some but not all nonfumigant nematicides are systemic, meaning the active ingredient is taken up by the plant and translocated throughout the plant. Further information about how nematicides work can be found in EDIS publication ENY-041, Movement and Toxicity of Nematicides in the Plant Root Zone.
There are a variety of different methods by which nematicides are applied, and they must be applied as specified on the label. Fumigant nematicides, and some liquid nonfumigants, may be injected into the soil with a shank or similar equipment. Some nematicides may be applied through irrigation systems, a process called chemigation. Chemigation can only be done through drip irrigation systems for some nematicides, particularly fumigants, while some nematicides, particularly liquid nonfumigants, may be applied through overhead sprinkler irrigation systems. Some liquid nonfumigants may be sprayed onto foliage, onto soil, or into the planting furrow. Depending on the product, granular nematicides may be applied in-furrow, as a broadcast, in a band over the closed furrow, or in a band where the crop will be planted. They must be mechanically incorporated into the soil. Application methods and the activity spectrum for agronomic crop nematicides are summarized in Table 2.
Nematicides are also available as seed treatments for some seed-grown agronomic crops. Generally, the seeds will come pretreated with the nematicidal product, so growers do not have to determine if a product is labeled for a given crop. Seed treatments may protect early growth stages of the crop from nematodes, resulting in some yield increase, but are unlikely to have large impacts on yield or nematode population densities because nematicides applied as a seed treatment are not distributed widely in the soil.
Table 1. Conventional fumigant and nonfumigant nematicides labeled for specific Florida agronomic crops. Contact: Zane Grabau, UF/IFAS Entomology and Nematology Department.1
Table 2. Properties of fumigant and nonfumigant nematicides labeled for specific Florida agronomic crops. Contact: Zane Grabau, UF/IFAS Entomology and Nematology Department.1